28F640L30, 28F128L30, 28F256L30
10.0
Power and Reset
10.1
Power-Up/Down Characteristics
Power supply sequencing is not required if VCC, VCCQ, and VPP are connected together; If
VCCQ and/or VPP are not connected to the VCC supply, then VCC should attain VCCMIN before
applying VCCQ and VPP. Device inputs should not be driven before supply voltage equals VCCMIN
.
Power supply transitions should only occur when RST# is low. This protects the device from
accidental programming or erasure during power transitions.
10.2
Power Supply Decoupling
Flash memory devices require careful power supply de-coupling. Three basic power supply current
considerations are: 1) standby current levels; 2) active current levels; and 3) transient peaks
produced when CE# and OE# are asserted and deasserted.
When the device is accessed, many internal conditions change. Circuits within the device enable
charge-pumps, and internal logic states change at high speed. All of these internal activities
produce transient signals. Transient current magnitudes depend on the device outputs’ capacitive
and inductive loading. Two-line control and correct de-coupling capacitor selection suppress
transient voltage peaks.
Because Intel® Multi-Level Cell (MLC) flash memory devices draw their power from VCC, VPP,
and VCCQ, each power connection should have a 0.1 µF ceramic capacitor connected to a
corresponding ground connection (e.g.VCCQ to VSSQ). High-frequency, inherently low-
inductance capacitors should be placed as close as possible to package leads.
Additionally, for every eight devices used in the system, a 4.7 µF electrolytic capacitor should be
placed between power and ground close to the devices. The bulk capacitor is meant to overcome
voltage droop caused by PCB trace inductance.
10.3
10.4
Automatic Power Saving (APS)
Automatic Power Saving (APS) provides low power operation during a read’s active state. ICCAPS
is the average current measured over any 5 ms time interval, 5 µs after CE# is deasserted. During
APS, average current is measured over the same time interval 5 µs after the following events
happen: (1) there is no internal read, program or erase operations cease; (2) CE# is asserted; (3) the
address lines are quiescent and at VSSQ or VCCQ. OE# may also be driven during APS.
Reset Characteristics
Asserting RST# during a system reset is important with automated program/erase devices because
systems typically expect to read from flash memory when coming out of reset. If a CPU reset
occurs without a flash memory reset, proper CPU initialization may not occur. This is because the
flash memory may be providing status information, instead of array data as expected. Connect
RST# to the same active-low reset signal used for CPU initialization.
50
Datasheet
INTEL [ INTEL ]
